Bioartificial pancreata promise physiological control of blood glucose levels, effectively treating Type I diabetes mellitus. Given the short supply of islets, development of alternative cell-lines appropriate for use in such devices is necessary. Transformed cells are a viable option, though their bioenergetic machinery may be inefficient. Because bioenergetics plays a role in the secretion of insulin, determining bioenergetic factors critical to insulin secretion may be important in selecting appropriate lines for inclusion into a bioartificial pancreas. This proposal will study cultures of entrapped transformed insulinoma cells and determine the impact of ATP and anaplerotic pathways on their ability to secrete insulin in response to an external glucose stimulus. NMR spectroscopic analysis of 13C and 31P data will provide a non-invasive quantitative assessment of the coupling between energy metabolism and insulin secretion, while non-NMR assays will derive glucose and oxygen consumption rates, as well as lactate, NH4+ and insulin production rates to provide a metabolic profile. Administration of specific inhibitors of the TCA cycle, anaplerotic pathways and oxidative phosphorylation, will aid in identifying factors critical to the initiation of insulin secretion. This knowledge will aid in the rational design and selection of insulin-producing cells.